Examples of early embodiments of similar devices are illustrated in the German Patent DE-A-2 030 525 and the U.S. Patent, U.S. Pat. No. 4,032,051.
However these prior art devices are not without disadvantages which compromise their operation during repeated cycles of compression and release of the tubular container to dispense the product.
The device disclosed in the German patent has the disadvantage of imperfect tangential wiping of the output orifice of the dispensing duct because of the presence, inside the duct, of a lifting tab extending in proximity to the output orifice, where it connects with the plate element at an angle that diminishes the wiping effect of the edge of the latter.
The device disclosed in U.S. Pat. No. 4,032,051, while having the advantage of tangential wiping of the output orifice, has the disadvantage of leaving a quantity of material exposed to the external environment after the orifice is closed, with the consequential risk of blockage of the orifice.
The object of the present invention is to eliminate the disadvantages associated with prior art devices while providing a device of simple structure and high reliability in use.